Numerical and analytical simulation of ballistic projectile penetration due to high velocity impact on ceramic target

Simulation and analysis of the projectile impact and penetration problem and its effects are among the practical topics that can be used to design bulletproof panel and military equipment, construction of impact and penetration resistant structures, design of projectiles with appropriate penetration strength and High performance noted. One of the most important parameters affecting penetration is the impact velocity of the projectile. The mechanism of penetration varies in different speed ranges. In this paper, Ansys Autodyn software is used for intrusion simulation. The simulation carried out in this study is based on the accuracy and physical conditions of the problem and the compatibility of numerical simulation with the governing analytical relationships indicates the validity and accuracy of the assumptions made in the simulation. In this study, we selected materials such as material behavior, grating, contact surfaces, and controls, as well as collision of the blunt projectile with angles of 0º,15º,30º,45º by of high velocity impact 1000 m/s with the same mass and diameter and shape of the projectile nose and properties. Ceramic materials are discussed. The result of the numerical simulation comparison shows relatively good agreement between them

Experimental Study of Fatigue Durability in Bending Effect on Welded Joints in Steel Profiles

Ships are always prone to fatigue through high periodic loads, usually caused by waves and changing load conditions. So, fatigue is an important factor in design. One of the reasons for fatigue in welding parts is variable bending loads. In this paper, a specimen of low-carbon steel T-Bar profiles is used, along with plates of the same type of steel that have been welded by the manual electrode welding process. To determine the distribution of static and dynamic forces created by welding, the specimens were subjected to bending (three-point loading) and tensile tests, and finally fatigue tests. The T-Bar Steel profile has more tolerance for fatigue loads than welded. The load T-Bar profile has not failed until the two million cycles, while the welding specimen has failed in about 3×105 cycles. Finally, strong penetrating welds should be used if a stronger welding joint is required

Optimization and Experimental Investigation of the Ability of New Material from Aluminum Casting on Pumice Particles to Reduce Shock Wave

Some materials, due to their inherent properties, can be used as shock and wave absorbers. These materials include foam and porous materials, in this study, specimens were made by casting aluminum on porous mineral pumice. Which can replace aluminum foam in some applications with lesser cost, at first, the material is compared with aluminum foam using compression test and quasi-static loading diagram. Which compares the diagrams of these two materials showing the similarity of their behavior in quasi-static loading. Initially, the elastic bending of the walls causes an elastic region in the stress-strain curve of the material. Then, the plastic collapsing of the cells forms a large and relatively smooth region along the elastic and after the plastic collapse of the cells, the area known as foam densification begins where the density of the foam closer to the density of its constituent material causes a sudden increase in the stress level in the specimen. These steps have also been seen in the quasi-static loading of aluminum foam. Then, by using numerical simulations with ANSYS AUTODYN and the shock tube test the ability of these specimens were investigated to reduce the shock wave. The behavior of the material in this case is also very similar to the results of previous studies on aluminum foam

Experimental and numerical optimization study of shock wave damping in aluminum panel sandwich

Sandwich panels with polymer composite and light core composites are widely used in aircraft and spacecraft, vessels, trains, submarines, and cars. Due to their high strength to weight ratio, high stability, and high corrosion resistance, these structures have become particularly important in the industry. Reduction in impact energy, shock waves, and noise in many industries, including the automotive and military industries. Porous materials have always been the focus of attention due to their shock-reducing effects in various protective applications. For this reason, the study of physics governing shock propagation problems in porous media is of particular importance, and the complexity of the governing equations also results in the numerical solution of these equations with many computational problems and costs. In this paper, shock wave damping is investigated numerically and experimentally in aluminum blocks with porous grains scattered inside aluminum. The deformations of the specimens in numerical simulation and experimental testing have been compared. The results show that this material behaves similarly to the aluminum foam in both static loadings (practical pressure testing) and dynamic loading (explosion simulation) results, again similar to aluminum foam

Numerical and Experimental Analysis of Stacking Sequences Effects in Composite Mechanical Joints under Impact Loadings

Composite structures in the field of advanced and modern structures in engineering design and according to high specification of composite materials such as high strength to weight ratio use in various industries such as aerospace, marine. One of the most important fields that Researchers have paid less attention to that is to investigate the effect of stacking sequence on the strength of mechanical joints under impact loading. In view of changing the mechanical properties of composite materials by changing the arrangement of layers, in this study, the effect of different orientation of layers on the strength of pin joints in glass-epoxy composites under low-velocity tensile impact has been investigated. Using the Abaqus software and the finite element method, the impact simulation and the force applied to the mechanical joint were analyzed. To evaluate the simulations, the results of the finite element method have been compared with the experimental results. By observing the results, the introduced finite element model is well-considered and is well-matched with the result of the experimental dataset, which made it a valuable tool for predicting the strength of multi-layer composite materials under impact loadings. Using the results of the model, one can analyze the distribution and type of stress and strain in each layer of composite.&nbsp

Numerical and analytical simulation of ballistic projectile penetration of high velocity impact on ceramic target

Simulation and analysis of the projectile impact and penetration problem and its effects are among the practical topics that can be used to design bulletproof panel and military equipment, construction of impact and penetration resistant structures, design of projectiles with appropriate penetration strength and High performance noted. One of the most important parameters affecting penetration is the impact velocity of the projectile. The mechanism of penetration varies in different speed ranges. In this paper, Ansys Autodyn software is used for intrusion simulation. The simulation carried out in this study is based on the accuracy and physical conditions of the problem and the compatibility of numerical simulation with the governing analytical relationships indicates the validity and accuracy of the assumptions made in the simulation. In this study, we selected materials such as material behavior, grating, contact surfaces, and controls, as well as collision of the blunt projectile with angles of 0º,15º,30º,45º by of high velocity impact 1000 m/s with the same mass and diameter and shape of the projectile nose and properties. Ceramic materials are discussed. The result of the numerical simulation comparison shows relatively good agreement between them

Analytical Study of Nonlinear Vibrations of Marine Risers by Newton Harmonic Balance Method

In this paper, using Newton's Harmonic Balance Method (NHBM), nonlinear vibrations of marine risers are investigated. The Newton harmonic method is approximate and similar to the February series method used for linear oscillator. Many researchers have conducted studies using numerical or approximate methods. Harmonic balance method, which itself has limitations in application. Generally, nonlinear vibration issues are of great importance in physics, mechanical structures, and other engineering research. Vibration response, stability, and frequencies are the main components of a system's vibration check. This method continues to be able to study a wider range of nonlinear differential equations. First, the Hamilton vibration equation is obtained. The effect of various parameters such as riser length and initial displacement of the upper support, etc. on the riser frequency has been investigated and then the equation has been solved, which shows acceptable accuracy after comparing the results of this article with previous research

Investigation of Failure Criteria and Experimental Process of the Composite Specimen with Mechanical Joints under Tensile Loading

Generally, composite materials are used to obtain better engineering properties, including higher hardness, greater strength, lower weight, heat resistance, moisture and corrosion, which are not present in homogeneous materials such as metals, which are more commonly used in composite design. In this article, experimental study of the composite specimen with mechanical joints under tensile loading, joints of composite material structures, failure criteria in composite materials, tensile impact test is investigated. The results of research work it shows that maximum strength, the hand lay-up can be designed with [0º, 45º, 90º, -45º] s and layers with 45º fibers is very important, because these fibers in these layers have a significant role in increasing the resistance of the piecework under shear stresses due to the passage of stress lines along the hole; In other words, the maximum cut occurs at a 45º angle, and these layers resist this shear stress

Validation and Optimization of Thermophysical Properties for Thermal Conductivity and Viscosity of Nanofluid Engine Oil using Neural Network

In this study, the thermophysical properties of thermal conductivity and viscosity of a motor oil nanofluid were investigated using experimental data and artificial neural network. NSGA II optimization algorithm was used to maximize thermal conductivity and minimum viscosity with changes in temperature and volume fraction of nanofluids. Also, to obtain the viscosity and thermal conductivity values in terms of nanofluid temperature and volume fraction with 174 experimental data, neural network modeling was performed. Input data include temperature and volume fraction, and output is viscosity and thermal conductivity. Various indices such as R squared and Mean Square Error (MSE) have been used to evaluate the accuracy of modeling in the prediction of viscosity and thermal conductivity of nanofluids. The coefficient of determination R squared is 0.9989 indicating acceptable agreement with the experimental data. In order to optimize and finally results as an objective function, the optimization algorithm is presented and the Parto front and its corresponding optimum points are presented where the maximum optimization results of thermal conductivity and viscosity occur at 1% volume fraction

Analytical Investigation of the Vibrational and Dynamic Response of Nano-Composite Cylindrical Shell Under Thermal Shock and Mild Heat Field by DQM Method

In this paper, the vibrations and dynamic response of an orthotropic thin-walled composite cylindrical shell with epoxy graphite layers reinforced with carbon nanotubes under heat shock and heat field loading are investigated. the carbon nanotubes were uniformly distributed along the thickness of the composite layer. The problem is that at first there is a temperature change due to the thermal field in the cylinder and the cylinder is coincident with the thermal field, then the surface temperature of the cylinder rises abruptly. Partial derivative equations of motion are coupled to heat equations. The differential quadrature method (DQM) is used to solve the equations. In this study, the effects of length, temperature, thickness and radius parameters on the natural frequencies and mid-layer displacement are investigated. The results show that increasing the outside temperature reduces the natural frequency and increases the displacement of the system. Radial displacement results were also compared with previous studies and were found to be in good agreement with previous literature. Increasing the percentage of carbon nanotubes also increased the natural frequency of the system and decreased the mobility of the middle layer